This invention relates to high pressure coupling devices, and more particularly to a quick-disconnect coupling assembly for coupling and decoupling gas or liquid operated equipment to and from the source whether under pressure or not.
Quick disconnect coupling devices are used to connect fluid lines for agricultural and industrial equipment, for example, to a source of fluid under pressure, such as that provided by a pump or a tractor. Such couplings commonly have a check valve in each coupling half, which is closed when the parts are disconnected, but which is opened as the result of the connecting of the coupling halves together. It is known that such couplers generally do not disconnect easily under pressure, because disconnection of the coupling members requires pushing one coupling member into the other against the high-fluid pressure. Attempts have been made to solve this problem by balancing fluid pressures acting on the check valves, by designing coupling members with different inner dimensions for the coupling halves, or by providing biasing arrangements which provide controlled operation of the check valves during coupling and uncoupling.
For the most part, attempts at developing fluid coupling devices which enable disconnection under pressure have resulted in the introduction of further flow control members such as pistons, poppet valves, ball check valves and the like, into the fluid flow path provided through the couplers. However, restrictions caused by internal workings of fluid checking devices, including the check valves normally used and other flow control members introduced to facilitate coupling and decoupling, create excessive pressure drop across the assembled couplers. Such pressure drop, in turn, causes extreme heat to develop at the coupling device which may result in breakdown of fluid seals used in present couplers. Such fluid flow restriction also results in wear and tear on the hydraulic pumps as well as on the equipment being used by causing the equipment to fail to respond as quickly as is desired. This is because restrictions prevent the hydraulic fluid from flowing swiftly and freely through the coupler. For example, in couplers presently in use, typically the fluid is pumped through a space of 1/10th of a square inch. The pump in the tractor, or other machinery, pumps approximately 18-22 gallons per minute. Obviously, when this much fluid is pumped through a space of 1/10th of a square inch, restriction of the fluid flow will cause a resulting pressure drop with an attendant heat buildup. Due to the restricted flow of the hydraulic fluid, as the hydraulic control levers are operated by the operator, a smooth response of the equipment will not always occur so that the equipment may exhibit a jerking effect when being raised or lowered. Such operation is hard not only on the equipment but also on the hydraulic system of the tractor which controls the equipment.
As indicated above, previous attempts to alleviate the problems associated with coupling and uncoupling hydraulic coupling units under pressure conditions usually have resulted in the introduction of further fluid flow control elements into the coupling devices and in the fluid flow passage they provide between the hydraulic hose connected to the pressurized hydraulic fluid source and hydraulic hose connected to the equipment controlled by the fluid. This approach not only increases the number of parts susceptible to wear, but also makes servicing of the coupling devices virtually impossible. In many cases, such couplers are neither serviceable nor repairable.